Passive safety systems for vehicles may include pre-tensioners, which reduce the slack in a seatbelt restraint when a collision is detected; inflatable seatbelt harnesses for better load distribution; and inflatable seat bolsters for improved lateral support during a collision.
These passive safety systems are typically used only once a collision has already occurred. Further, because these passive safety systems require extremely fast reaction times, many are destructive, that is, they are capable of being used only once before requiring replacement.
Some active communications systems include audible or visual warnings to alert occupants to different conditions relative to a vehicle. For example, lane-keeping systems may generate a beeping sound or display a visual icon to alert the occupant if the vehicle drifts too close to a lane line while in operation.